Environment overrides
Nine environment variables tune runs without touching the attributes — useful in CI. They are resolved by the adapter (Testo's interceptor, PHPUnit's trait), not the engine itself: PropertyRunner never reads the process environment, so a custom harness driving it directly opts into the same table only if it chooses to. Core supplies the parsing — EnvironmentOverrides and CorpusFactory — so both adapters mean the same thing by the same value.
| Variable | Effect |
|---|---|
PROPERTY_RUNS | Positive integer that overrides every property's run count (dial runs up in CI). |
PROPERTY_SEED | Integer seed used for any property whose attribute omits seed (replay a whole suite). An explicit attribute seed still wins. |
PROPERTY_VERBOSE | Logs every run's generated arguments and, on failure, every accepted shrink step (shrink step 3: x=63 -> 51) — see exactly what a replayed seed feeds the property and how the shrinker descends. |
PROPERTY_DERANDOMIZE | Derives an unset seed from the property id instead of drawing one, so a locally found bug reproduces in CI before any corpus entry exists. See Derandomized runs. |
PROPERTY_PHASES | Comma-separated subset of examples, corpus, random, shrink — the same set as PropertyConfig::$phases. An unknown name is an error, not a silently skipped phase. See Run phases. |
PROPERTY_EDGE_CASES | mixin (default) or none; none turns off the numeric boundary bias without shifting the sequence a seed produces. See Boundary bias. |
PROPERTY_PATH | Replays a recorded shrink descent instead of searching for it. Requires PROPERTY_SEED (or an attribute seed) — a path without the seed it was recorded on is refused rather than applied to a different run. See Replaying a shrink path. |
PROPERTY_DB | Enables the regression corpus: a directory path, or redis://host[:port][/db][?prefix=key-prefix&timeout=seconds] (rediss:// for TLS) for a store shared between CI and developers. Any other scheme is an error. Unset means the feature is off and nothing is written. See Regression corpus. |
PROPERTY_DB_PASSWORD | The AUTH password for a Redis PROPERTY_DB. Kept out of the DSN on purpose: PROPERTY_DB is echoed in the diagnostics and lands in CI logs, and credentials in the userinfo of a DSN are refused outright. |
Unset, empty, and "off"
Unset and empty both mean "not given": the attribute's own value stands. For the two flags — PROPERTY_VERBOSE and PROPERTY_DERANDOMIZE — 0, false, off and no (case-insensitively, surrounding whitespace ignored) turn the feature off, and any other value turns it on. A shell exports words as readily as digits, and PROPERTY_VERBOSE=false enabling verbose output is a surprise nobody needs.
A malformed value is an error naming the variable, never a fallback to the default: PROPERTY_RUNS=abc stops the suite instead of quietly running 100 times.
PROPERTY_RUNS=10000 vendor/bin/testo
PROPERTY_SEED=1712345678 PROPERTY_VERBOSE=1 vendor/bin/testo
PROPERTY_PHASES=examples,corpus vendor/bin/phpunit
PROPERTY_DB=build/property-db vendor/bin/testo
PROPERTY_DB=redis://redis:6379/2?prefix=suite-a: PROPERTY_DB_PASSWORD=… vendor/bin/testo